1. Technical Field
The present invention relates to a fixing device installed in an image forming apparatus, such as a printer, a copier, etc., and in particular to a fixing device capable of fixing a toner image onto a recording medium by applying heat and pressure thereto.
2. Related Art
Conventionally, as a toner image fixing device used in an image forming apparatus, such as a printer, a copier, etc., a heat roller-type fixing device is known. The heat roller-type fixing device generally includes a pair of rollers (e.g. a fixing roller and a pressing roller) each having an internal heat source, such as a halogen heater, etc. The pair of rollers rotates while heated and pressed against each other, forming a contact nip (e.g. a fixing-nip) therebetween. In such a system, a transfer medium bearing an un-fixed toner image thereon is conveyed through the fixing-nip (i.e., a contact nip) of the heat roller-type fixing device, so that the un-fixed toner image can melt and be fixed onto the transfer medium in the fixing-nip.
In recent years, in accordance with a growing demand for saving energy and shortening a waiting time in heating a fixing system, such as a warm-up time, a first time to print, etc., a so-called on-demand fixing unit is widely adopted, in which an endless belt is composed of a thin belt or film and the like instead of a heat roller to reduce a heat capacity of the fixing system as a whole, thereby improving effectiveness of heat transfer to the recording medium while greatly shortening the waiting time.
In a known example of this kind of fixing system, a fixed member (e.g., an opposed member) contacts an inner circumferential surface of a fixing belt sliding thereon and is pressed against a pressing roller via the fixing belt forming a fixing nip between the fixing belt and the pressing roller. The recording medium is conveyed to the fixing nip to fix the toner image borne on the recording medium onto the recording medium.
For example, JP-2002-108119-A discloses a technology in which a reflector reflects heat emanating from a halogen heater toward an opposite side of a film guide that guides and supports an endless film belt in a fixing nip formed on the endless film belt by pressing a pressing roller against the endless film belt as the belt travels in a prescribed direction through the nip. Accordingly, propagation of heat from a heat source can be given directionality by the reflector.
In such a conventional fixing device, however, when the reflector is to be deployed at a prescribed location relative to the above-described heat source, the reflector is generally fixed to a reinforcing member using a fastening member, such as a screw, etc. In addition, to fix the reflector with the screw, the reinforcing member is generally drilled and tapped as well, thereby incurring a cost increase due to these additional manufacturing processes.
Further, since the fastening member needs to be disposed in the constricted confines found inside the loop formed by the fixing belt so as not to interfere with other components, constricted layout of the components may be restricted or assembly complicated by the need to use a machine tool to attach the fastening member.